The gaseous current being thus formed, sweeping through the interior atmosphere of the tubes and serpentines, would carry before it the air which would be expelled by turning the tap A. By means of an indiarubber pipe placed upon the nozzle of this tap, this current would be received in a vase containing water. The air would escape, the ammonia would remain In the water, and when the absorption was complete, and no more bubbles were formed on the surface, it would be seen that all the air had escaped; it would then he necessary to close the tap h. This being done, nothing would remain in the interior but the liquefied ammonia, the vapour of which, immediately attaining the maximum of tension, would at once fill the space left empty by the expelled air. If then by any accident the temperature of the generator b became higher than that of the condenser d, vapour would at once bo formed in the receiver b, which would proceed to condensation in the receiver d, until the balance of temperature was restored. This action would be all the more rapid in proportion to the rapidity with which the vapour is induced in the vacuum; and would be also in proportion to the condensation.
Thenco there would be a relation between the force of the condensing action in d, the promptitude of vaporisation in b, and the energy of refrigeration of the body passing in the tubes and round the casing. Now, this body is no other than the atmospheric air freely entering at the orifice a and penetrating the tubes, drawn by the increase of density communicated to it by refrigeration, and causing it to descend the chimney. If the surfaces are sufficient, the temperature will remain equal between 4 and d; therefore, if the water which reaches the condenser is at 8° or 10° C, the air which emerges at the lower part will have that temperature; descending the chimney a, this air passes by the conduits i to freely distribute itself in the localities where it is necessary to produce a cooler atmosphere.
Unquestionably this arrangement, susceptible of modifications according to circumstances, is ingeniously conceived; according to the inventor, it has the merit of cheapness and utility. But it appears somewhat complicated, and this complication materially limits its application in many instances, especially as we have at the present time an engine which, if not constructed in so original a manner as the engine of Teller, offers guarantees of sucess of similarly weighty kind, and is more economical. The employment of am-monia in itself is an obstacle, among others, to the application of the apparatus. In industrial matters it is constantly desired to find, not elegant combinations, but those which are simple and practical. In some breweries and chocolate factories, this apparatus might be of signal use; but, despite its utility, despite the incontestable claims of the inventor, it cannot be looked upon as a final solution of the.
The question seems to have been answered by a system founded opon well-known principles, and which has the merit of being universally applicable. This new method is allied to the first class spoken of. In this, both water and a ventilator are again employed, but the dispositions of the system are completely different; to that there is a wide difference between them. Duvoir cooled the air by pulverising the water; Nezeraui and Garlandat lay no claim to this pulverisation of water; they content themselves with filtering the air through water, and thus purifying and cooling It. Furthermore, in this new system the simplicity is incontestable, the utility is evident, and the economy is:
The original idea is due to Nezeraux, and the apparatus constructed in consequence was jointly perfected by Ne-zeraur and Garlandat with signal success. The principle already existed in an apparatus previously designed by Nezeraux, and used in the workshops of a well-known constructor. This apparatus, upon which has been bestowed the name of hydro-atmospheric condenser, is composed of two distinct parts, the condenser a properly so called, and the refrigerator b; - the condenser of a series of tubes assembled between two plates forming part of a cylindrical cating hermetically closed, of a pump which serves at once for pierced with holes of small diameter, and of a ventilator, the current of which passes through the orifice d. The steam escaping from the cylinder penetrates to e, disperses through the space between the tubes, condenses itself by contact, and produces a vacuum. The water which has just condensed the steam passes above the perforated plate /, upon which a current of air is continually in action from above and beneath, which divides the water and instantly cools it; it falls into the tank g, whence it is pumped by means of the tube h and brought back by i; thence it passes uniformly through all the tubes over the whole extent of the refrigerating surface by means of little fluted plugs or similar contrivances at the top of each tube.
The conducted steam is drawn off at the base of the apparatus at k by means of a pump, to be restored to the feeding tank. Applied to condensers, the refrigerator effects a considerable economy of water, and produces other advantages which it is unnecessary to mention here, not concerning the subject under consideration.
If the steam-boiler add steam be suppressed in this apparatus, and the perforated metallic plate and ventilator be only retained, we obtain another apparatus (Fig. 16).
Through the perforated plate a, either of metal or some other material, from beneath to above, the ventilator 6, set in motion by the hand, or, in the case of a more considerable application, by some mechanical motor, keeps up a current of air which passes through the numerous holes of the plate. Above this plate cold water is introduced by the pipe c, furnished with a regulating tap; the water passes into a water-pipe, whence it issues uniformly over the plate, which is slanted in such a manner that the thickness of water shall not exceed certain limits; in some cases, ice or chemical solutions, as those of phenic acid, may be substituted, according to the application of the apparatus. The pressure exercised by the propelled air suffices to maintain the water on the surface of the plate, and prevents it passing to the lower part. The water flows slowly on to the plate, and after having passed over and given its coolness to the air which penetrates it, finally reaches the other pipe, by which it runs to the issue at d; in most cases this water is again useful for other purposes. As to the cooled air, it penetrates into the upper part of the apparatus, escaping by the tube e, and reaches the places where it is wanted.